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gen_audio_resampler_filter.c: Precalculate loop-invariant bessel(beta). 

Minor optimization in offline code.
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Ryan C. Gordon 2022-05-26 10:44:01 -04:00
parent 822cf0b34b
commit 5968f3d828
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1 changed files with 2 additions and 1 deletions
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build-scripts/gen_audio_resampler_filter.c
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@ -74,11 +74,12 @@ kaiser_and_sinc(float *table, float *diffs, const int tablelen, const double bet
{ {
const int lenm1 = tablelen - 1; const int lenm1 = tablelen - 1;
const int lenm1div2 = lenm1 / 2; const int lenm1div2 = lenm1 / 2;
const double bessel_beta = bessel(beta);
int i; int i;
table[0] = 1.0f; table[0] = 1.0f;
for (i = 1; i < tablelen; i++) { for (i = 1; i < tablelen; i++) {
const double kaiser = bessel(beta * sqrt(1.0 - pow(((i - lenm1) / 2.0) / lenm1div2, 2.0))) / bessel(beta); const double kaiser = bessel(beta * sqrt(1.0 - pow(((i - lenm1) / 2.0) / lenm1div2, 2.0))) / bessel_beta;
table[tablelen - i] = (float) kaiser; table[tablelen - i] = (float) kaiser;
} }